What does the text identify as the ultimate limit of detectability of weak signals in almost every area of measurement?
Explanation
The chapter emphasizes that the theoretical and practical limit to measuring a small signal is the presence of noise. Noise, which consists of unwanted random fluctuations, can obscure the desired signal, making it undetectable. All efforts in low-noise design are aimed at minimizing this noise floor to improve measurement sensitivity.
Other questions
In the high-common-mode voltage differential amplifier shown in Figure 7.27, what is the primary function of the op-amp U2?
What is the specified minimum CMRR for the INA106 precision differential amplifier?
How does the Burr-Brown INA117 achieve its large common-mode voltage range?
What is a primary disadvantage of the follower-based differential amplifier shown in Figure 7.31?
In the classic three-op-amp instrumentation amplifier (Figure 7.32), what is the key advantage of the input stage design?
What is the purpose of the 'guard' output in an instrumentation amplifier like the one in Figure 7.33?
Under what circumstance would a bootstrapped power supply, as shown in Figure 7.35, be necessary for an instrumentation amplifier?
What is the defining characteristic of Johnson noise?
According to the text, a 10k resistor at room temperature, measured with a bandwidth of 10kHz, has an open-circuit rms voltage of approximately how much?
Which type of resistor listed in the text has the lowest typical excess noise (1/f noise)?
How is the Noise Figure (NF) of an amplifier defined?
What is the 'Big fallacy' associated with Noise Figure that the text warns against?
An amplifier with a noise figure of 3dB has a noise temperature that is approximately what?
In the simple noise model for a transistor or amplifier, what does the term 'en' represent?
For low source resistances, which component of the amplifier noise model generally dominates the total noise?
According to the text, for low-noise design with a given source, what is the general tradeoff between a bipolar transistor and a FET?
What is the primary characteristic of the two-op-amp instrumentation amplifier configuration shown in Figure 7.36?
In a differential amplifier, how does the input-referred voltage noise (en) for the differential pair compare to that of a single-ended amplifier configuration?
What is the typical RTI (Referred-To-Input) voltage noise in the 0.1-10Hz range for the AMP-01A instrumentation amplifier according to Table 7.5?
Based on Table 7.5, what is the minimum DC CMRR specified for the INA101C at a gain of 1?
According to Table 7.5, which instrumentation amplifier has the highest slew rate at G=1k?
What is the typical settling time to 1 percent for the AD521 at a gain of 1k?
If you add two uncorrelated noise signals with rms amplitudes of 3 uV and 4 uV, what is the rms amplitude of the resulting signal?
What is the primary physical origin of voltage noise (en) in a JFET?
To achieve the lowest voltage noise (en) when using a JFET, how should the drain current (ID) generally be set?
What is 'noise resistance' (Rn) in the context of amplifier noise analysis?
When is it advisable to use a transformer at the input of a low-noise amplifier?
In the context of the noise model for low-noise design with transistors, how is the total amplifier noise voltage, ea(amplifier), calculated?
According to Figure 7.49, which plots total amplifier input voltage noise, what is the value of the noise resistance (Rn) for the LM394 input stage at 1kHz and Ic = 50uA?
What is a primary source of current noise (in) in a bipolar transistor?
In the noninverting feedback amplifier configuration of Figure 7.56, where do the additional noise voltage terms (beyond the basic amplifier en and in) arise from?
According to the graph in Figure 7.58A, which op-amp exhibits the lowest input noise voltage (en) at a frequency of 10Hz?
In Figure 7.58B, which op-amp has the lowest input noise current (in) at 1kHz?
What is the key difference between shot noise and Johnson noise?
How does the text describe the noise performance of a circuit using a T network in the feedback path, as in Figure 7.30?
According to the text, what is a simple way to increase the transconductance (gm) of a JFET and therefore decrease its voltage noise?
What is the typical input impedance of the INA105 precision differential amplifier?
What does the text suggest is the main cause of degraded CMRR in a differential amplifier when source resistances are present?
For the AD624 instrumentation amplifier mentioned in the text, what is the specified gain linearity?
What is the key functional difference between a standard differencing amplifier and a two-op-amp instrumentation amplifier (Figure 7.36)?
The text warns that for the 2SD786 low-noise transistor, an unusually low base spreading resistance (rbb) of what value is needed to realize the lowest values of en?
What type of noise is characterized by having equal power per decade of frequency and is sometimes called 'pink noise'?
To correctly measure the rms voltage of Gaussian noise, by what factor should you multiply the reading from a simple averaging AC voltmeter?
What is the equivalent 'brick-wall' noise bandwidth (B) for a simple single-pole RC low-pass filter with a 3dB frequency of f_3dB?
Which instrumentation amplifier from Table 7.5 is identified as a 'CAZ type'?
What does the text identify as a major drawback of the INA117's method for achieving a large common-mode voltage range?
What is the primary purpose of the 'SENSE' and 'REF' terminals on an instrumentation amplifier like the one in Figure 7.33?
According to the amplifier noise model, when driven by a signal source with impedance Rs, the total input-referred noise voltage squared is the sum of three components. What are they?
What is 'signal guarding' as described in the text and shown in Figure 7.80?